PROBLEM TO BE SOLVED: To provide an inspection technique which is capable of discovering the weld zone defect arising at the boundary between the pipe and cast iron of a stave cooler.;SOLUTION: Figure (d) indicates the defective boundary part and indicates that a welding preventive agent 44 lacks locally and that the weld zone 45 is made by direct tight contact of the cast iron 16 and the pipe 11 there. Ultrasonic waves 43 reflect on the inside surface of the pipe 11 but advance rectilinealry in the weld zone 45. (e) Is an echo wavelength diagram in correspondence to (d) where an S echo is admitted but a B1 echo does not appear. (c) Indicates the echo in the sound boundary part where the B1, B2 and B3 echoes are admitted. The significant difference exists between the sound (c) and the unsound (e). Namely, unless the B1 echo arises, the presence of a serious defect is highly doubtful and even when the B1 echo arises, the defect of a light degree is doubtful if this echo is weak.;COPYRIGHT: (C)2001,JPO
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